Forgot to remove a couple of things when cleaning up the code for the
previous commit

Re-coded this feature (which had been temporarily removed due to the
old code being reliant on the obsolete QuickTime library).

Due to QWidget::showFullScreen having side-effects on OSX (setting the
dock and menubar to autohide, making it impossible to then set them as
hidden), the calls to that method were replaced with
UBPlatformUtils::showFullScreen(QWidget *). This function then calls
QWidget::showMaximized() on OSX, or QWidget::showFullScreen() on Linux
and Windows.

It is currently still impossible to switch smoothly between showing or
hiding the dock on OSX; current behaviour is to hide it all the time,
even in desktop mode.

- Removed commented out obsolete code that had been added
- Removed objects that were never used (mAudioOutput, audioFormat etc)
- Re-made changes that had been reverted since commit cdb56333

Migrated all QuickTime-related code to modern AVFoundation / Core Video
/ Core Media equivalents.
Audio support was temporarily removed; to be re-established ASAP.

Beginnings of doxygen-style function documentation was added

- Replace #include <QtWebKit> by #include <QtWebKitWidgets>.

- Replace uniboardTool by openboardTool.
- Replace UBMimeType::UniboardTool by UBMimeType::OpenboardTool.

by "openboardtool://apps".

("http://get.openboard.org/update.json").
=> the url do not exists.

removed redundant OBCocoa files / namespace; moved functions to UBPlatformUtils, which serves the same purpose

Application compiles and runs, with some caveats. Full list of changes:

- minor changes related to Qt4->Qt5 API differences

- Replaced calls to Carbon framework by Cocoa

- Removed registering of AE event handler. Seems to be done
automatically in Qt5.

- temporarily removed Podcast functionality, pending (presumably)
complete re-write due to Quicktime being obsolete in newer OS X
versions.

- Created OBCocoa namespace, and associated files src/core/OBCocoa.h/.mm, to
handle OS X - specific system calls. Currently used only by
UBApplication, but can in the future provide a useful interface between
the cocoa framework and OB, to avoid having too much OSX-specific code
in various files

update repository.